Commutator-cylinder for dynamo-electric machines.



e. M. EATON. CQMMUTATOR CYLINDER FOR DYNAMO ELECTRIC MACHINES.

, APPUFIATIQN HLED IAN-5,19I7. 1,292,598 Patented Jan 28, 1-919.

WITNESSES:

INVENTOR George M faiafl.

BY wvzzfg u ATTORNEY UNITED STATES PATENT OFFICE.

GEORGE M. EATON, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

COMMUTATOR-CYLINDER FOR DYNAMO-ELECTRIC MACHINES.

Specification of Letters Patent.

Patented Jan. 28, 1919.

Application filed January 5, 1917. Serial No. 140,743.

To all whom it may concern:

Be it known that I, GEORGE M. EATON, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Commutator-Cylinders for Dynamo-Electric Machines, of which the following is a specification.

My invention relates to the construction of commutator cylinders for dynamo-electric machines, and it has for its object to provide a commutator cylinder that is particularly adapted for use in connection with dynamo-electric machines of the high-voltage type.

In the construction of commutator cylinders for high voltage, it is essential that suificient insulation be provided in order to prevent electrical discharges between the conducting segments which are at machine potential and the clamping rings which are at ground potential. The obvious expedient is to increase the length of the creepage path which is usually defined as the shortest distance over the exposed surfaces of the insulating material between the live parts and the ground. The desired results have heretofore been obtained by merely extending the insulation beyond the conducting segments, as shown in Patent No. 1,046,743, in which is shown and described a commutator cylinder that is provided with a clamping ring having an annular portion projecting beyond the ends of the conducting segments. This projecting portion is covered with a layer of insulating material, and the length of the creepage path is substantially dependent upon the amount that the clamping ring projects beyond the ends of the conducting segments. The abovementioned construction has, at times, been found impracticable, however, because of the space limitations existing in certain types of apparatus, such as railway motors.

According to the present invention, I provide a high-voltage commutator cylinder having a safe creepage path wherein the length of the commutator cylinder is actually decreased, as compared with existing types. I propose to accomplish this result by employing a novel type of clamping ring that is provided with a curved or polygonal end surface that extends inwardly with respect to the end of the commutator cylinder.

This surface is covered with a layer of insulatlng material, thereby providing a creepage path of maximum length, the major portion of which is located within the overhanglng end portions of the commutator segments. In the accompanying drawings, Figure 1 1s a vlew, partially in section and partially in side elevation, of a portion of a commutator cylinder embodying 'my invention; Fig. 2 is a view, partially in section and partially in end elevation, of the parts shown in Fig. 1, and Fig. 3 is a fragmentary view showing a modification of the means employed for securing the insulating material.

A plurality of conducting and insulating segments 1 and 2 are alternately disposed upon a spider 3'and are secured in position thereon by means of a clamping ring 4 having a V-shaped annular end face which engages a V-shaped groove provided in the segments 1 and 2. The ring 4 is adapted to be forced into engagement with the segments by means of bolts 5. The ring is further provided with an outer circumferential surface 6 that extends beyond the ends of the segments 1 and 2 and a curved or polygonal end surface 7 that extends inwardly with respect to the end of the commutator cylinder, so that the major portion of the surface 7 is located within the overhanging end-portions of the commutator segments. The ring 4 is further provided with an inner circumferential flange 8 for a purpose to be hereinafter described.

A layer 9 of insulating material (preferably mica) is interposed between the segments 1 and 2 and the ring 4 and conforms to the inner surface of the segments 1 and 2. The layer 9 covers the circumferential surface 6 and terminates in a laterally-extending flange or ring 10. The circumferential surface 6 is provided with a countersunk portion 11 within which is located a layer 12 of insulating material that eXtends around the corner of the ring 4 and covers the surface 7. The layer 12 is provided with a laterally-extending flange 13 adj acent to the flange 8 of the ring 4. The layer 12 is secured to the ring 4 by means of a protective hood 14 that is preferably composed of a material having both insulating and fire-proofing qualities, such as asbestos cloth. The hood 14 is provided with a folded-over portion 15 that is located within the annular space bounded by the flange 10 of the insulating layer -9 and a groove 16 that is provided in the ends of the segments 1 and 2. The hood 14 is preferably formed of a number of gores 17 which are stitched together in order to. facilitate their assembly.

In assembling a commutator cylinder conthe hood 14 are then stitched together for a short distance along their outer edges, one

seam being left open to allow the hood to be wrapped around the insulating layer 9 within the flange 10. The last seam is then stitched and the hood' is secured to the ring 4 by means of lashings 18 that fill the space within the flange 10. The hood 14 is then folded over the lashings, as shown at 15, and the unstitched portions of the gores 17 are held in the position shown in dotted lines wherein their adjacent edges come together and the end portion of each gore is folded over to form a rim 19, after which the seams are stitched completely. The completed hood 14 is then substantially inside out, and may be readily pulled over the surface 7 of the ring 4 after removal of the form engaging the same. The laterally extending rim 19 then fits closely within the flange 13 of the insulating layer 12. The hood 14 and the insulating layer 12 are then secured to the fiange 8 of the ring 4 by means of suitable lashings 20 that are applied at intervals around the flange 8. The remaining forms having been removed from the clamping ring 4, it is then applied to the assembled segments 1 and 2 of the commutator cylinder, the folded over portion 15 of the hood then being partially located within the groove 16 that is provided in the ends of the segments. The hood 14 is preferably finally impregnated with a suitable insulating compound so that any pores or openings in its material will be completely filled.

A modification of the manner of securing the hood 14 is shown in Fig. 3, wherein the hood is lapped over the flange 8 and, together with an L-shaped reinforcing ring 21, is secured by lashings 20,'as described with reference to Fig. 1.

From the foregoing, it is apparent that a commutator cylinder constructed in accordance with my invention w1ll have a greatly increased creepage distance as com-- pared with other commutator cylinders of the usual construction and of the same overall length. Furthermore, the-exposed sur-:

1. A commutator cylinder 'comprisinga clamping-- ring having a curved end surface extending inwardly with respect to'the end of said commutator cylinder and a layer of insulating material covering said surface.

2. A commutator cylinder comprising a clamping ring having a curved end surface located within the overhanging end portions of said commutator cylinder and a layer of insulating material covering said surface.

3. A commutator cylinder comprising circumferentially arranged conducting and insulating segments and an insulating surface located within the end portions of said assembled segments.

4. A commutator cylinder comprising circumferentially arranged conducting and insulating segments and a curved surface of insulating material located within the endv portions of said assembled segments.

5. A commutator cylinder comprising circumferentially arranged conducting and insulating segments, a clamping ring therefor, a layer of insulating material interposed between said segments and said ring and a second layer of insulating material having a portion secured to the outer circumferential surface of said ring and another portion located within the end portions of saidassem bled segments.

6. A commutator cylinder comprising circumferentially arranged conducting and insulating segments, a clamping ring therefor, a layer of insulating material interposed between said segments and said ring and a second layer of insulating material having a portion located in a circumferential groove provided in said ring and another portion covering the end surface'of said ring and extending within the end portions of said assembled segments.

7. In a commutator cylinder, the combina-' tion with conducting and insulating segments and a clamping ring for said segments having a portion thereof projecting beyond the ends of said segments and provided with a curved end surface, of a layer of insulating material for covering said curved surface and means coacting with said projecting portion for maintaining said layer in position.

8. In a commutator cylinder, the combination with conducting and insulating segments, and a clamping ring for said seg:

ments having a portion thereof projecting beyond the ends of said segments and provided with a curved end surface, of a layer of insulating material for covering said curved surface and means coacting with said projecting portion and the ends of said segments for maintaining said layer in position.

9. In a commutator cylinder, the combination with circumferentially arranged conducting and insulating segments, a clampin rin for said segments having a curved end surface extending within the overhangingend portions of said segments and a layer of insulating material interposed between said segments and said ring, of a layer of insulating material having a portion located between said first-named insulating layer and said rin and another portion covering the end sur ace of said ring.

10. The combination with a ring-shaped member having an outer circumferential surface, an inner circumferential flange and a curved end surface extending between said outer surface and said flange, of a layer of insulating material covering said end sur face and means coacting with said outer surface and said flange for maintaining said layer in position on said ring.

11. The combination with a ring-shaped member having an outer circumferential surface, an inner circumferential flange and a curved end surface extending between said outer surface and said flange, of a layer of insulating material having a. portion thereof surrounding said outer surface and another portion thereof covering said end surface, and a protective hood for said layer having ortions coacting with said outer surface and' said flange, respectively, to maintain said layer in position on said ring.

12. The combination with a ring-shaped member having an outer circumferential surface, an inner circumferential flange and a curved end surface extending between said outer surface and said flange, of a layer of insulating material surroundin r said outer surface, a second layer of insulating material having a portion fitting within said first-named layer and another portion covering said end surface, and means coacting with said outer surface and said flange for maintaining both layers in position on said ring.

13. The combination with a ring-shaped member having an outer circumferential surface, an inner circumferential flange and a curved end surface extending between said outer surface and said flange, of a layer of insulating material surrounding said outer surface, and terminating in a laterally ex tending annular portion, a second layer of insulating material having a portion located within said annular portion and another portion covering said end surface and a protective hood for said insulating layers having an outer folded-over portion in engagement with said annular portion and an inner circumferential portion secured to the flange on said ring.

In testimony whereof, I have hereunto subscribed my name this 27th day of Dec. 1916.

GEORGE M. EATON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

